New shadow chancellor John McDonnell has said he wants to change the capitalist economic model and eradicate "unacceptable" poverty.

The veteran left-winger, new party leader Jeremy Corbyn's long-term ally in Westminster, has backed renationalisation of the banking system, effectively printing money to fund government investment, and a 60% tax rate on earnings above £100,000.

Mr McDonnell, who boasts in his Who's Who entry that his hobbies include "fermenting (sic) the overthrow of capitalism", told Channel 4 News: "The emphasis is on ferment, which was about brewing. It means ensuring people understand what capitalism is, and we talk together about how we change it because it is failing people at the moment.

"I think change is a gradual process ... but at the end of the day, I do want to transform it."

He said part of the shadow chancellor's job was to reform capitalism and "put forward an alternative to what's happening to people at the moment".

Mr McDonnell said he was "not particularly interested in a tax on income", but was more concerned with organisations not paying taxes and "laughing all the way to the bank".

He also described how the current economic situation has left "unacceptable" levels of people in poverty.

Mr McDonnell said he understood why his appointment was not met with acclaim from Labour grandees.

He said: "I'm a backbencher, I've been opposed to virtually everything New Labour has done, I've been voting against them on many things like privatisation, Iraq.

"I've had to oppose a lot of things and sometimes that's meant swimming against the stream. That has meant, at times, Jeremy and I have been isolated. But actually, we were right on many of these things.

"I think we have been proven right and I think the tide is now with us."

Mr McDonnell also gave a short explanation about the basis of comments he made in 2003 when he described the IRA as "brave".

He told Channel 4 News he did it for the sake of the Northern Ireland peace process.

He said: "Some of us had to go out there - I might not have chosen the right words - and actually explain to them they could stand down with dignity.

"I know as a result of that I got attacked, but actually it worked. And if it saved one life, it was worth it."